The attack late Thursday by the rebels, known as Houthis, was the most dramatic border incident since Saudi Arabia launched an intense campaign of airstrikes against the rebels just over a month ago. It also brought to 11 the number of Saudi soldiers killed so far in border skirmishes during the air campaign.

Houthis are still capable of launching major operations despite the airstrikes that have relentlessly targeted their positions and those of their allies — military units loyal to former president Ali Abdullah Saleh.

In the border attack, Houthi fighters in tanks and armored vehicles struck “border posts and control points” in the southern Saudi region of Najran on Thursday night, the kingdom’s Defense Ministry said.

Saudi forces, backed by fighter jets, repelled the attack and “dozens of the militiamen were killed. Three soldiers of the ground troops were martyred,” according to the statement, which did not clarify how far across the border the attackers came.

The kingdom’s security forces said on April 11 that more than 500 Houthi rebels have been killed in border clashes, mostly in the area of Najran. The kingdom has offered the families of each slain soldier 1 million Saudi riyals, or about $267,000, to compensate for their loss.

Since the airstrikes began, Saudi Arabia boosted its troop numbers along the roughly 1,300 kilometers (800 miles) long border with Yemen. The troops frequently fire at suspected rebel positions with both cannon and mortar fire.

The area across the border is considered a Houthi stronghold. The Houthis managed to take several scattered Saudi villages in the southern border region of Jizan in 2009, during the kingdom’s last war with the rebels.

Last week, during an AP trip to Saudi military positions in Jizan and Najran, the commander of Najran forces, Brig. Gen. Abdullah al-Shehri, said the border situation was stable. The war has so far not included a ground force operation in Yemen but al-Shehri said his forces were prepared for any eventuality.